<template>
  <!-- 鼠标移入停止 移出开始 事件 -->
  <div class="xtx-carousel" @mouseenter="stop()" @mouseleave="start()">
    <ul class="carousel-body">
      <li
        class="carousel-item"
        v-for="(item, index) in sliders"
        :key="index"
        :class="{ fade: index === current }"
      >
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="" />
        </RouterLink>
      </li>
    </ul>
    <a href="javascript:;" class="carousel-btn prev" @click="toggle(-1)"
      ><i class="iconfont icon-angle-left"></i
    ></a>
    <a href="javascript:;" class="carousel-btn next" @click="toggle(1)"
      ><i class="iconfont icon-angle-right"></i
    ></a>
    <div class="carousel-indicator">
      <!-- 点击事件使current等于当前点击的索引 -->
      <span
        v-for="(item, index) in sliders"
        @click="current = index"
        :key="index"
        :class="{ active: index === current }"
      ></span>
    </div>
  </div>
</template>

<script>
import { ref, watch } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    // 轮播图数据
    sliders: {
      type: Array,
      default: () => []
    },
    // 是否播放
    autoPlay: {
      type: Boolean,
      default: false
    },
    // 延时
    duration: {
      type: Number,
      default: 3000
    }
  },
  setup (props) {
    // 控制显示图片的索引
    const current = ref(0)
    // 设置定时器
    let timer = null
    // 设置定时器自动轮播的方法
    const play = () => {
      timer = setInterval(() => {
        current.value++
        if (current.value >= props.sliders.length) {
          current.value = 0
        }
      }, props.duration)
    }
    // 监听轮播图数据
    watch(
      () => props.sliders,
      (newVal) => {
        // 如果有数据和需要做动画
        if (newVal.length && props.autoPlay) {
          current.value = 0
          // 调用轮播方法 从第一张开始
          play()
        }
      },
      // 深度监听
      { immediate: true }
    )
    // 鼠标移入 停止轮播
    const stop = () => {
      if (timer) clearInterval(timer)
    }
    // 鼠标移出 开始轮播
    const start = () => {
      if (props.sliders && props.autoPlay) {
        play()
      }
    }
    // 左右图标点击事件
    const toggle = (step) => {
      // 定义相加后的索引
      const newCurrent = current.value + step
      // 最后一张++ 回到第一张 => 索引=0
      if (newCurrent > props.sliders.length - 1) {
        current.value = 0
        return
      }
      // 第一张-- 回到数组长度-1 即最后一张 索引=数组长度-1
      if (newCurrent < 0) {
        current.value = props.sliders.length - 1
        return
      }
      current.value = newCurrent
    }
    return {
      current,
      stop,
      start,
      toggle
    }
  }
}
</script>
<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      // fade  使当前的图片透明度和权重都在其他图片之上
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }

  ::v-deep .carousel-btn.prev {
    left: 270px;
  }
  ::v-deep .carousel-indicator {
    padding-left: 250px;
  }
}
</style>
